The present invention is particularly related to puffer-type compressed-gas circuit-interrupters of the type in which only a single internal pressure of gas, such as sulfur-hexafluoride (SF.sub.6) gas, for example, is utilized within the interrupting structure. A difference of gas pressure for arc interruption is achieved by appropriate piston action, that is, relative movement of an operating cylinder to a piston structure. Attention may be directed to U.S. Pat. Nos.: 3,839,613--Tsubaki et al; 3,602,670--Calvino Teijeiro; 3,849,616--Clavino Teijeiro; 3,670,124--Calvino Teijeiro; 3,670,125--Calvino Teijeiro; and 3,712,969--Calvino Teijeiro.
As well known by those skilled in the art, the relative motion between the movable operating cylinder assembly and the fixed piston achieves a desirable compression of gas within the intervening compression chamber, which compressed gas is utilized during arc interruption by generally forcing the compressed high-pressure gas, such as SF.sub.6 gas, for example, through a movable insulating nozzle structure to direct the high-pressure gas flow intimately into engagement with the established arc drawn within the movable insulating nozzle to effect the latter's extinction.